From 4352b8aee98005853aa63f57d6377282de17a33f Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 23 Aug 2026 13:28:57 -0700 Subject: Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ... --- samples/pidfd/pidfd-metadata.c | 120 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 120 insertions(+) create mode 100644 samples/pidfd/pidfd-metadata.c (limited to 'samples/pidfd/pidfd-metadata.c') diff --git a/samples/pidfd/pidfd-metadata.c b/samples/pidfd/pidfd-metadata.c new file mode 100644 index 000000000..c459155da --- /dev/null +++ b/samples/pidfd/pidfd-metadata.c @@ -0,0 +1,120 @@ +// SPDX-License-Identifier: GPL-2.0 + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#ifndef CLONE_PIDFD +#define CLONE_PIDFD 0x00001000 +#endif + +#ifndef __NR_pidfd_send_signal +#define __NR_pidfd_send_signal -1 +#endif + +static int do_child(void *args) +{ + printf("%d\n", getpid()); + _exit(EXIT_SUCCESS); +} + +static pid_t pidfd_clone(int flags, int *pidfd) +{ + size_t stack_size = 1024; + char *stack[1024] = { 0 }; + +#ifdef __ia64__ + return __clone2(do_child, stack, stack_size, flags | SIGCHLD, NULL, pidfd); +#else + return clone(do_child, stack + stack_size, flags | SIGCHLD, NULL, pidfd); +#endif +} + +static inline int sys_pidfd_send_signal(int pidfd, int sig, siginfo_t *info, + unsigned int flags) +{ + return syscall(__NR_pidfd_send_signal, pidfd, sig, info, flags); +} + +static int pidfd_metadata_fd(pid_t pid, int pidfd) +{ + int procfd, ret; + char path[100]; + + snprintf(path, sizeof(path), "/proc/%d", pid); + procfd = open(path, O_DIRECTORY | O_RDONLY | O_CLOEXEC); + if (procfd < 0) { + warn("Failed to open %s\n", path); + return -1; + } + + /* + * Verify that the pid has not been recycled and our /proc/ handle + * is still valid. + */ + ret = sys_pidfd_send_signal(pidfd, 0, NULL, 0); + if (ret < 0) { + switch (errno) { + case EPERM: + /* Process exists, just not allowed to signal it. */ + break; + default: + warn("Failed to signal process\n"); + close(procfd); + procfd = -1; + } + } + + return procfd; +} + +int main(int argc, char *argv[]) +{ + int pidfd = -1, ret = EXIT_FAILURE; + char buf[4096] = { 0 }; + pid_t pid; + int procfd, statusfd; + ssize_t bytes; + + pid = pidfd_clone(CLONE_PIDFD, &pidfd); + if (pid < 0) + err(ret, "CLONE_PIDFD"); + if (pidfd == -1) { + warnx("CLONE_PIDFD is not supported by the kernel"); + goto out; + } + + procfd = pidfd_metadata_fd(pid, pidfd); + close(pidfd); + if (procfd < 0) + goto out; + + statusfd = openat(procfd, "status", O_RDONLY | O_CLOEXEC); + close(procfd); + if (statusfd < 0) + goto out; + + bytes = read(statusfd, buf, sizeof(buf)); + if (bytes > 0) + bytes = write(STDOUT_FILENO, buf, bytes); + close(statusfd); + ret = EXIT_SUCCESS; + +out: + (void)wait(NULL); + + exit(ret); +} -- cgit v1.3.1